I’ve been playing with my Raspberry Pi again. Bought the Sense Hat, which is an add-on card that has temp, humidity, and air pressure sensors, a tiny joystick, and a large 8 x 8 multi-color LED display, and software to draw graphics and scroll messages across it. Having fun.
One of the things I find frustrating is that the Raspberry Pi 3 (and others) have ARMv8 64-bit chips in them, but nobody has released a 64-bit Linux for it. The Raspberry Pi Foundation wants to maintain backwards compatibility at all costs, and they never want to make things too complex for people who want to learn.
Found this page describing the actual RPi boot sequence really fascinating. The GPU boots up first!